package acwing.search;

import java.util.Scanner;

public class cubeRoot_ {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        double num = sc.nextDouble();
        double result = cubeRoot(num);
        System.out.printf("%.6f\n", result);
    }
    public static double cubeRoot(double num){
        double value = 1e-10;
        double left = 0;
        double right = Math.abs(num) + 1;
        while(right - left > value){
            double mid = left + (right - left)/2;
            if (mid * mid * mid >= Math.abs(num)){
                right = mid;
            }
            else {
                left = mid;
            }
        }
        if (num < 0) return -left;
        else return left;
    }
}
